Remote-control system



Jan. 15, 1929. 1,698,772

. F. w. SCHRAMM REMOTE CONTROL SYSTEI Filed April 20, 1926 IN VEN TOR Z'Jahramm/ ATTORNEY Patented Jan. 15, 1929.

UNITED STATES FRED W. scHRAMM, .03 BBQQKL N N W YORK, A S Q To E IQ N TELEPHONE AND TELEGRAPH COMPANX, A CORPORATION REMOTE-CONTROL srsrnm.

Application filed A pri1 20, 1926. Serial No. 1Q8,38Q.

This invention relates to remote control systems, and particularly to arrangements for controlling from a n-iain or central station a plurality of vacuum tube amplifiers each located at a remote station.

In wire and radio broadcasting and similar systems it frequently occurs that amplifiers are placed at subscribers residences and other points remote from the main or central program distributing center. Heretot'ore in order to turn suehampliliers on or off and to supervise their operation it has been necessary to pr vide an attendant for each amplifier or group of amplifiers, Thus, considerable eXpense has been incurred, especially in systems in which the amplifiers were isolated. herever an attendant is not present to care for an amplifier, a failure of the amplifier may not be evident ,atthe main or central station until the subscriber or receiving station reports to the main or central station that no program is being received. In a system where more than one amplifier is used a report from the subscriber does not of itself locate the trouble and a large amount of time is lost in tracing it.

This invention discloses a system which is comparatively cheap and simple to operate in which some or all of a plurality or" ampliliers each located at a remote station may be turned on or ofi simultaneously from the main or central station and signals obtained at the main or central station indicating which amplifiers are operating. a program being supplied to the various amplifiers at the remote stations sig is are given to the. operator at the main or cen .ral station by means of signaling devices thereat indicating which amplifiers are being supplied with the program. Furthermore, when the operation o1 one or more amplifiers fails to remain in an operating condition the operator at the main or central station will be notified of such failure by the various signals thereat.

l invention will be better under tood from the detailed description hereinafter ifoh lowing when read in connection with the accompanying drawing showing one embodiment of i he invention.

A main or central station I is connected by main lines ML and ML to remote stations 1 and 1 respectively, each of these remote stationshaving a vacuum tube amplifier thereat for receiving the program transhus when mitted by the main or central station 1,. It Wlll be understood, however, that while .onlv two remote stations have been shown hereih the lnvention is not so limited, but a plurahty of remote stations may be connected to the main .or central station without .(leparting from the spirit of the invention and the scope of the appended claims' A source of signals S is connected .to the main line ML through a transformer T Signals are received from the main line ML at the signal receiving circuit 8., at Station I the signals being transmitted through transformer T the amplifier AM and the transformer T There are line keys at .the main station I .each corresponding to one of the remote stations. The line key corresponding to the remote station I may be turned to its on, off .or neutral position. hen the line key is turned to its..on position a swinger l closes a contact 2. When the line he; is

thrown to its off position aswinger 3 closes a contact 4L and a swinger-'5 ciosesa contact 6, said swingers 3 and omoving synchronously, being connected by a strip of insulation. KVhen the line key is thrown to its neutral posit-ion swinger 1 closes contact Tandswinger 3 closes contact. 8. Similarlythe liue lcey corresponding to the remote station I may he turned to its on, off and neutral ositions, the apparatus at the main station 1 employed in connection with the remote station 1, being primed. It will be understood, however, that while only two line keys have been shown at the main statiomone corresponding to each of the remote stations,

a plurality .oi' 'line keys may be provided at the main station I to operate a plurality of remote stationsgeach liuehey corresponding to a remote station.

hen the line hey corresponding to the remote station I is thrown to its on position, line relay A, at the main stationand .line relay B at the remote station are energized, the circuitincluding a sourceo-t direct current P, contact 2 and swingerl 0f the line key, the winding of line relay A the secondary winding of transformer T bothcon- (luctors of the main line MLin parallel, .the primary winding of the transformer T the armature contact-9 of a relay-D andt-he winding of the relay B. 'lflvhen th .l ne r lay 1 becomes energized its armeture ;1;() is attract- ..ed closing .a circuit which includes ,a'signal or other indicating device at the the circuit including a source of direct current P, the armature 10 and its contact and a signal lamp L,. When the line relay B at the remote station 1, becomes energized, a circuit is closed energizing a control relay C at the remote station, this circuit including the armature 11 and the contact associated with the line relay B, the winding of the control relay C, source of potential G and the armature 12 and its contact associated with the alternating current relay E. When the control relay G becomes encrgized its armature closes a circuit interconnecting the source of potential G with the cathode of the amplifier AM, this circuit including the armature 13 and the contact associated with thecontrol relay C, the source of potential G a resistance R and the oathode of the amplifier AM. Furthermore, when the control relay C becomes energized, the plate circuit of the amplifier AM is closed, the circuit including the armature 13 and the contact associated with the control relay C, the source of potential G the winding of the relay D, the primary winding of the transformer T,, the anode and cathode of lamp L,, main station,

. the amplifier AM and the leads 1 1.

The current flowing in this platecircuit, and'consequently the current flowing through the winding of the relay D increases until a normal state is reached. hen this normal state is reached the relay D operates attracting its armatures 9 and 15, armature 15 closing its contact so as to form a path parallel to the path established by the armature 11 and the contact associated with the line relay B. Thus the control relay C remains operated even when the line relay B becomes deenergized. lVhen the relay D operates opening the contact associated with the armature 9, a circuit is opened which includes the line relay B at the remote station, the line relay A, and the source of direct current P at the main station. when the line relay A, at the main station becomes deenergized, its armature 10 is released, opening the circuit which includes the signal lamp L,.

The line key at the main station remains in its on position so that when the current in the plate circuit of the amplifier AM diminishes for any reason whatsoever, as, when the filament thereof burns out, or when the source of potential G fails, etc, the relay D will release its armatures because insufiicient current flows through the winding thereof to hold these armatures closed. Thus the armature 9 will close the contact associated with it and the line relay B at the remote station I will be connected in circuit with the line relay A, and the source of direct current P at the main station thereby operating these line relays. Consequently, the signal lamp L, at the main station lights also. When the line relay B at the remote station operates, it

again energizes the winding of the control relay C so that the amplifier AM may start up again if the interruption is only momentary. However, if the amplifier AM does not operate, that is if insufficient current flows through the plate circuit thereof, the signal lamp L, at the main station will remain lighted. Similarly when there is trouble with the amplifier Ah associated with the remote station i the signal lamp L, at the main station will become lighted.

hen the line key is thrown to its"off position, the swinger 8 closes contact 4c and connects the source of alternating current G, to an alternating current relay E at the remote station, the circuit including the generator G,, contact 4t and'swinger 3 of the line key, condenser 0,, the secondary wincing of the transformer T,, both conductors of the main line ML in parallel, the primary winding of the transformer T a condenser C, and the winding of the alternating current relay Vihen the winding of the alternating current relay E is energized its armatures 12 and 17 are attracted, the armature 12 opening the circuit interconnecting the winding of the control relay C and the source of potential G When the winding of the control relay 0 becomes deenergized, its armature 13 is released opening the circuit which interconnects the source of potential G and the cath ode and the anode of the amplifier Al l. When the armature 17 associated with the alternating current relay E closes its contact, a shunt path is established around the winding of the relay B, this shunt path including the choke coil F, the armature 17 and its contact. W hen the current flowing in the plate circuit decreases, the armatures 9 and 15 associated with the relay D are released so that the line relay A, and the source of direct current P at the main station are again connected to the remote station 1 the circuit now including armature 1? and its contact, the choke coil F, the armature 9 and its contact associated with relay D, the primary winding of the transformer T both conductors of the main line ML in parallel, the secondary winding of the transformer T the winding of the line relay A,, contact 6 and swinger of the line key and the source of direct current P. Thus, when the line relay A, hecomes energized the signal lamp L, associ ated therewith lights, indicating that the amplifier AM at the remote station I, has been turned off. Just as soon as the signal lamp L, lights indicating that the relay 1) at the remote station I, has released its armatures, the line hey is then thrown to its neutral po sition, removing the source of direct current and the source of alternating current from the main line ML.

A master key is provided for simultaneously turning on or oil the amplifiers located at a plurality of remote stations. When the master key is thrown on, a swinger 2O closes contact 21. vVhen the master key is tm'ned oil a swinger 22 closes a contact 23 and swing er 20 closes contact E l. When the master key is thrown into its neutral position, the swingers 20 and 2 are isolated from their contacts. If it is desired to turn on the amplifiers corresponding to some of the remote stations and to leave the other amplifiers at other remote stations oil, the line keys corresponding to the amplifiers to be turned otl are connected to the oil positions and then the master key is turned on.

Inasmuch as the arrangements of this invention have been described with particular reference to the connection of the cathode and anode of an amplifier to a source of direct current, it is to be distinctly understood that With slight modifications a source of alter nating current may be employed instead of a source of direct current within the scope of the invention.

It will be understood that while the arrangements of the invention have been shown with particular reference to a wire broadcasting system, this invention may be embodied in the radio broadcasting and other systems without departing from the spirit of the invention and the scope of the appended claims.

Vr'hile tlu= arrangements of this invention have been shown in one particular embodiment, it will be understood that the invention may be embodied in other and widel Varied organizations withoutdeparting from the spirit of the invention and the scope of the appended claims.

\Vhat is claimed is: V

1. In a system for controlling from a main station a plurality of vacuum tube amplifiers each located at a remote station, in combination, a plurality of line relays at the main station one corresponding to each remote station, a plurality of line relays one at each remote station, a source of potential at the main station, a plurality of sources of potential one at each remote station, a plurality of line keys at the main station one corresponding to each remote station, each line key operating a circuit interconnecting the source of poteir tial and the line relay at the main station and the line relay at the corresponding remote station, a plurality of control relays one at each remote station, each control relay being associated with the corresponding line relay at the remote station and controlling the operation of the corresponding vacuum tube amplifier by the source of potential at said remote station, a plurality of indicating devices at the main station one corresponding to each remote station, each indicating device indicating whe her or not the vacuum tube amplifier at the corresponding remote station is operating, and means for rendering each indicating device operative when the vacuum tube amplifier at the corresponding rent a t re main station, a plurality of sources 7 of potential one at each remote station for energizin the vacuum tube amplifier thereat, a plurality of alternating current relays one at each remote station, a plurality of line keys at the main station one corresponding to each remote station, each line key closing a circuit which includes a source of direct urrent and the line relay at the main station and the line relay at the corresponding remote station when the vacuum tube amplifier said remote station to be energized, each line key closing a circuitwhich includes the source of alternating current at the main station and the alternating current relay at the corresponding remote station when the vacuum tube amplifier at said remote sta tion is to be deenergized, a plurality of control relays, one each remote station, each control relay being associated with the corresponding line relay at the remote station and controlling the operation of the corresponding vacuum tube amplifier by the source of potential at said remote station, and a plurality of indicating devices at the main station, one corresponding to each remote station, each indicat'ng device indicating whether or not the vacuum tube amplifier at the corresponding remote station is operating.

3. in a system for controlling from a main station a plurality of vacuum tube amplifiers each located at a remote station, in combination, a plurality of line relays at the main station one corresponding to each remote station, a plurality of line relays one at each remote station, a source oi potential at the main station, a plurality of sources of potential one at each remote station, a master key at the main station operating a plurality of circuits, each circuit interconnecting the source of potential and the line relay at the main station and the line relay at the correspond relays one at each remote statio.-, each control relay being associated with the corre sponding line relay at the remote station and controlling the operation of the corresponding vacuum tube amplifier by the sou cc of potential at said remote station, a plurality of indicating devices at the main station one corresponding to each remote station, each indicating device indica ing whether or not the vacuum tube amplifier at the corresponding remote station is operating, and means for rendering each indicating device operamg remote station, a plurality of control corresponding remote tive when the vacuum tube amplifier at the corresponding remote station has failed to operate satisfactorily.

l. In a system tor controlling from a main station a plurality of vacuum tube ai'nplifiers each located at a remote station, in combination, a plurality of line relays at the main station one corresponding to each remote station, a plurality of line relays one at each remote station, a source of direct current and a source of alternating current at the main station, a plurality of sources of potential, one at each remote station for energizing the vacuum tube amplifier thereat, a plurality of alternating current relays one at each remote station, a plurality of line keys at the main station, one corresponding to each remote station, each line key closing a circuit Which includes the source ot' direct current and the line relay at the main st tion and the line relay at the corresponding mote station When the vacuum tube amplifier at said remote station is to be energized, each line key closing a circuit Which includes the source of alternating current at the main station and the alternating current relay at the station when the vacuum tube amplifier at said remote station is to be deenergized, a master key at the main station for simultaneously operating all of the line keys thereat, a plurality of control relays one at each remote station, each control relay being associated with the corresponding line relay at the remote station and controlling the operation of the corresponding vacuum tube amplifier by the source of potential at said remote station, and a plurality of indicating devices at the main station one corresponding to each remote station, each indicating device indicating When the vacuum tube amplifier at the corresponding remote station is operating.

In a system for controlling from a main station a plurality of vacuum tube amplifiers each located at a remote station, in combination, a plurality of line relays at the main station. one corresponding to each remote station, a plurality of line relays one at each remote station, a source of direct current at the main station, a source of alternating current at the main station, plurality oil sources of potential one at each remote station for energizin the vacuum tube amplifier thereat, a plurality of alternating current relays one at each remote station, a master key at the main station operating a plurality of circuits two corresponding to each remote station, one circuit including the source of direct current and the line relay at the main station and the line relay at the corresponding remote station, the other circuit including a source of alternating current at the main and the alternating current relay at the corresponding remote station, a plurality of control relays one at each remote station, each control relay being associated With the corresponding line relay at the remote station and controlling the operation of the corresponding vacuum tube amplifier by the source of potential at said remote station, and a plurality of indicating devices at the main station one corresponding to each remote station, each indicating device indicating when the vacuum tube amplifier at the corresponding remote station is operated.

6. In a system for controlling from a main station a plurality of vacuum tube amplifiers each located at a remote station, in combination, a plurality of line relays at the main station one corr sponding to each remote stat-ion, a plurality of line relays one at each remote statioina source of potential at the main station, a plurality of sources of potential one at each remote station, a plurality ct dicating devices at the main station, one corresponding to each remote station, aplurality of line keys at the main station one corresponding to each remote station, each line key operating a circuit interconnecting the source of potential and the line relay at the main station and the linerelay at the corre sponding remote station, the indicating devices indicating Which amplifiers are connected to the main station, the line relay at each remote station connecting the amplifier to the source of potential thereat, and means whereby the source of potential at each remote station may be disconnected from the amplifier thereat on the failure of said amplifier, said indicating devices also indicating which amplifiers have failed.

7. A system for controlling from a main station an amplifier located at a remote station, comprising two relays one at the main station and the other at the remote station, means whereby said relays may become ener gized When the amplifier at the remote station is to be started and stopped in operation, a source of potential at the remote station, means for connecting said source of potential to the amplifier When the relay at the remote station becomes energized, and means for deenergizing said relays When the amplifier is receiving sufiicient operating current from the source of potential, and indicating means at the main station for indicating when the amplifier at the remote station has started operating and has stopped operating, said indicating means also indicating a failure in the satisfactory operation of said amplifier.

In testimony whereof, I have signed my name to this specification this 19th day of April, 1926.

FRED l/V. SCHBAMM. 

